The invention relates to an angle position sensor for detection of the angle position of a component which can rotate about a rotation axis, in particular a throttle valve position sensor, having a magnet ring which has one or more parts and is connected in a rotationally fixed manner to the component, coaxially with respect to the rotation axis, is magnetized transversely with respect to the rotation axis and is surrounded on its external circumference by a ferromagnetic outer shielding ring, and having a magnetic sensor element which is arranged in a fixed position radially within the magnet ring.
Known angle position sensors such as these are in the form of magnetoresistive sensors or Hall sensors.
In the case of magnetoresistive sensors, the magnet ring produces an exciting field which rotates about the active center of the sensor element. The use of resistance elements connected in the form of a Wheatstone bridge to form the sensor element results in a sine function and a cosine function, so that the angle to be measured can be determined by forming the arctan.
Hall sensors produce a signal which is proportional to the magnetic induction. They have good resistance to magnetic disturbance fields, since such fields are kept away from the Hall sensor by the outer shielding ring.
These known angle position sensors require a central arrangement within the magnet ring, in order to make it possible to produce the sinusoidal and cosinusoidal signals correctly.
Furthermore, it is not possible to use a component which can rotate and is composed of a ferromagnetic material since, otherwise, this would result in a highly inhomogeneous field profile. Since the magnetic reluctance in iron is several orders of magnitude less than that in air, a greater proportion of the lines of force is deflected toward the component which can rotate. This is evident by the fact that the field amplitudes differ widely in the vertical and horizontal directions. Without complex correction, the signals that are produced are no longer suitable for angle calculation.
The use of a Hall sensor to determine angles is also difficult when using a component which can rotate and is formed from a ferromagnetic material, since this component is arranged in the immediate vicinity of the flux guide pieces of the Hall sensor, so that a large proportion of the magnetic flux is short-circuited by the component which can rotate. Exact matching of the characteristics of the sensor is possible only in the assembled state, and this is associated with increased production costs.